Checking fixture



June 25,1935. .1. c. DRADER CHECKING FIXTURE Filed Nov. 15, 1929 2 Sheets-Sheet l N\ ON 2 Sheets-SheetZ km m wwh June 25; 1935 J. c. DRADER CHECKING FIXTURE Filed NOV. 15, '1929 Patented June 25, 1935 1 OFFICE CHECKING FIXTURE Joseph C. Drader, Detroit, Mich, assignor to Michigan. Tool Company, a corporation of Michigan Application November 15, 1929, Serial No. 407,500

1 Claim.

This invention relates to testing machines particularly suited for worm generating cutters. The main objects of this invention are to provide an improved testing machine which 'will 5 visually indicate a minute irregularity in the surface of a piece of work; to provide a'testing m'a'chinefor accurately checking the angularity of. the sides of the teeth of a Work unit such as a gear 'cu'tterfand to provide a simple and accurate machine of this character which is readily adjustable to'test pieces of work which vary in size within a wide range.

An illustrative embodiment of this invention is"shown in the accompanying drawings, in

which Fig.1l is a top plan view of the improved testing machine, with a piece of work in position thereon," and with its. position shown in dotted 1 outline.

when reversed,

Fig. 2 is a View in'front elevation of the same. Fig. 3 is afragmentary view in front elevation, with a master gauge form on the work supporting spindle.

Fig. 4 is a' sectional view taken on the line 4 4 of Figl'2, looking in the direction indicated by the arrows.

In the construction shown in the drawings, an elongated bed plate frame 5 is provided on its upper side with horizontally disposed parallel tively.

ways. 6 and 'l which are bounded along their outer sides by upstanding flanges 8 and 9 respecdisposed studs i l -and t2 which extend upwardly,

the bed plate parallel with the ways.

T pp

ends ofthe studs" ii and I2 are threaded into the carriage l and the heads thereof are in spaced relation to the under side of the bed plat-;.l.BDWZshaped leaf. springs l and it are interposed between the heads of the studs, and are mounted thereon at their medial points with the ends thereof frictionally bearing against the under side of the bed plate.

The bed plate 5 is also preferably provided with a longitudinally extending, medially disposed guide bar ll rigidly mounted on the top side thereof by studs I3 and i9 which pass up through suitable apertures in the bed plate and screw into the bar.

slotted at each' end thereof to snugly fit and slide on said guide bar.

Means is provided for sliding the carriage II) on its ways, and this. means preferably comprises a lead screw 20'journa1ed against axial move ment in an upstanding bracket 2! integrally formed on one end of the bed plate medially of the-ways 6 and l. The'screw 20 is threaded into the adjacent end of the carriage I0 and a'hand wheel 22 is shown as rigidly secured on the end thereof which projects through the bracket 2|, by a nut 23. A sleeve or collar 24 maybe interposed between the hand Wheel 22 and bracket 2!, and indexed to co-operate' with a mark on the bracket, for measuring movement of the carriage relative to the bed plate. A knurled headed set screw 25 is shown as threaded 1n the sleeve 2 l'for releasably securing it to the screw at any desired circumferential position.

The carriageit, at its rear side, is provided with an upstanding bracket 26, shown as integrally, formed thereon, which has a vertically disposed, parallel sided slot therein which provides guideways 21. The guideways 21 slidably sup port a gauge frame 28 (see Fig. 1) which is shown as embraced thereby and'which is provided with a nut 29 and washer'30 which bear against the rear face of' the'ways. '1

The top end of the slot whichforms the ways 21 is closed by a crosshead '31 secured by screws 32 to the top end of the bracket 26. The cross-- head 3i may snugly receive a vertically disposed lead screw 33 which is threaded through the gauge frame28 for adjusting said frame vertically with respect to the carriage Ill and bed plate-5. A handle 34, having a pair of upstand ing diametrically opposed pins .35 and 36,'is

shown as rigidly mounted on the top end of the lead screw 33 for facilitating manual rotation thereof.

A visual-indicatinggauge 31 is rigidly mounted on the frame 28 by a knurled headed screwv 38 which passes through alug 39 on thegauge and is threaded into the frame 28. The in-f dicator 3i is preferably graduated to one thousandth of aninch, and the face thereof is preferably rotatable so that all readings xmay be.

taken from zero, if desired.

The gauge frame 28 is shown as-provided with an arm it integrally formed thereon which extends downwardly and toward the end of the bed. plate opposite to the end having the lead screw for moving the carriage. The lower end of the arm 40 has a lever M pivoted thereon by a stud screw 12. One end of the lever may be bifurcated as shown at 43 to embrace a pin in the lower end of an indicator operating connection 44, and the other end thereof may have the form of a pointer or finger 45, adapted to contact with the surface of the piece of work to be tested, the

.lever 4| thus serving as part of a connecting means between finger 45 and gauge 31.

Any suitable means may be provided for supporting a work unit to be tested, and the illustrated means comprise an upstanding bracket arm 46 integrally formed on the bed plate 5 at the rear side and adjacent to one end thereof. The upper end of the bracket arm has one end of a suitably disposed work supporting spindle 41 rigidlysecured thereto, as by a nut", the-axis of said spindle being, in the illustrated instance, perpendicular to the plane of movement of the carriage 10. The other end of the spindle is shown as provided with retaining means in the form of a knurled hand nut 49 which abuts against a freely slidable spacing sleeve 50, interposed between the nut andapiece of work 5|. The piece of work 5| shown in Figs. 1 and 2 of the drawings is a, worm generating cutter in whichthe teeth 52 thereof have plane sides.

'-It will be evident that there must be some cylindrical surface to which each straight line elementcomprised in any tooth surface of the illustrated type is tangent; and any member :whiohprovides a surface sustaining this relation to successive corresponding surfaces provided by the teeth of any gear, any gear cutter or like work-unit that is to be tested is hereinafter referred to as a master cylinder or form,said

; member being suitable for use in the zero-setting of the pointer or-dial of gauge 31; and, in the operation of this device, it will accordingly be understood that, to establish a tangent plane at the desired level, a master cylinder form 53 may first be placed on the work spindle 41 and the carriage l and frame 28 may be moved until-the end of the finger 45 is on the top'dead center of the cylinder. In thus positioning the finger 45, suflicient pressure is placed thereon by appropriate vertical movement of the gauge frame 28 sothat the pointer hand of the gauge willmove 'eitherway from the set position all back lash or lostinotion between parts being taken up; The'indicator gauge is then observed '1 and preferably set with a zero reading.

The carriage is then withdrawn by rotating the handwheel 22 and lead screw 20,: and the cutter or otherwork unit to be tested put on the spindle 41 in the place of the master cylinder.

The carriage may then be moved until the finger 45,its tip being raised orv lowered, if necessary,

' isbrought opposite and into engagement with the outertip of a cutter tooth and the cutter rotated onlthe spindle until the reading is again zero. The cutter 5| may then be clamped by the hand'nut 49 and the carriage moved forward toward the spindle so as to cause the finger 45 to slide on the surface of the tooth. Depressions or raised spots as well as any error in the angularity of thatside of the tooth which is thus tested may be seen by observing the movement, it any, of the pointer on the gauge 31.

Each tooth is successively brought into and held in position as described, and when the same side of each tooth on the cutter has been thus examined, the cutter may be removed from the spindle and replaced in reverse position so that the opposite sides or faces of the cutter teeth may be similarly tested. In thus reversing the cutter, the nut 49 and collar 50 are removed to permit removal of the cutter 5|, and before the cutter is replaced in reverse position a suitable spacing collar is placed on the support and is then followed by the cutter, the latter being thus positioned for co-operation with the pointer 45; in case both of the sets of the faces of the teeth- 52 are alike, or comprise lines that either should be included in the mentioned tangential plane or should varytherefrom only in a predetermined manner, the above procedure may then be repeated.

Various sized cutters and pieces of work may be tested on this machine, appropriate to master cylinder forms being used anda corresponding" adjustment in any appropriate direction and/or plane being secured, as by moving the gauge frame 28 in its guideways by rotating the lead screw 33 in the appropriate direction.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing from the spirit of this invention, as defined by the following claim; and that the described method, as. applied to a cutter whose tooth surfaces should lie in substantially radial planes, comprises first determining a plane tangent to a cylinder having a fixed axis; zero setting a gauge'which is provided with a finger (said finger being then disposed insaid plane, as by reason of its engagement with a master form concentric with said axis): thereafter disposing a work unit concentrically with said'axis and so that a point in its surface that is to be tested lies in said plane and in engagement with said finger; and producing a relative parallel translatory movement between said unit and said gauge with reference to said plane while observing said gauge.

I claim:

A device for testing the teeth or thread of an element the sides of which are tangent to a circle, which includes, in combination, a base, a finger,

an indicator actuated thereby, an arbor upon' means for advancing said finger over said tooth I or thread to explore the surface thereof.

JOSEPH C. DRADER. 

